How hilarious and humbling would it be if it turns out we are actually just a farm planet for some alien race. Perhaps humans are a nutritious snack and Earth is located on an intergalactic pathway as sort of a rest stop. At some point in the future, these giant beings, three times the height of the Empire State Building will plop down on Earth, like four or five of them, near major cities and start scooping up people, thirty at a time and stuffing them in their mouths. Then, after about 5 handfuls, feeling refreshed, they look up, and BOING! They leap from Earth towards their next destination. And thus, we've served our purpose - a self-sustaining snack bar/rest stop on a galactic nature walk around the Milky Way, for the creatures that "actually" inhabit the universe.